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Khal
Joined: 26 Sep 2003
Posts: 4872
Location: Sunny and lovely interior BC, Canada
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 Posted: Mon May 08, 2006 1:22 pm Post subject: |
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Thanks sequential,
| sequential wrote: | | I think you are reading into this too much, i'm not saying the car has cancer and it is cato, i was just evaluating your dyno sheet. |
 I know she's not a junker!
| sequential wrote: | It is normal to see +/- .25-.5 psi when measured electronically , it wil give 3-6 bhp variation on the graph. Also most Dyno software has a smoothing feature that takes care of this so you get an average. you can next time ask the operator to do this or open the grids up , it all depends on how detail you would like the graph.
THe graph yes is smooth with the exception of the change after peak torque ( it appears ) but it is not always normal for the power to fall at the end , as at this boost power level you have not really started to extend the turbo, so trialing off is ususally from boost taper and or a very restrictive exhaust ( not likely until 1 bar ) but it is also possible the setup has started to fall after 6000 rpm ( i have never checked a stock 931 ) hence the roll off. |
Yeah, that's the sort of thing I wasn't sure of. Experienced people know what to expect but there's very few dyno plots of 924 Turbos so I've got little to compare it to. And I don't personally know anyone who's had it done before ('cept Kenodog but his has been highly modified).
Not 100% sure I'm gonna put the boost controller on it yet. I've gotta talk to crunchie 57 and get his opinion. He's been into the engine, he knows what's what...
| flosho wrote: | | Nice Kahl... Any video? |
Thanks but no video, unfortunately. From my previous post:
| Khal wrote: | | I couldn't vid the runs. Unfortunately, the dyno's setup in a warehouse-style workshop and it was just too dark to get a good picture (with my dodgy digicam) |
| flosho wrote: | | Hopefully I'll be able to get some dyno time too... |
Yeah, do it! It's cool 
| flosho wrote: | | 150 at 7.5 psi seems pretty good, considering stock US boost is 7 and we only have 155 crank hp. |
I actually thought it might read higher. But I'm certainly not dissappointed! I'm rather impressed with the old girl! 
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'80 924 Turbo |
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Khal
Joined: 26 Sep 2003
Posts: 4872
Location: Sunny and lovely interior BC, Canada
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| Posted: Fri May 12, 2006 5:33 pm Post subject: |
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Alrighty then... she's hittin' the dyno again tomorrow with 10psi
Anyone care to guess at the result?
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'80 924 Turbo |
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tj924
Joined: 15 Jul 2004
Posts: 957
Location: Toowoomba, Queensland, Australia
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| Posted: Fri May 12, 2006 5:38 pm Post subject: |
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| Khal wrote: | Alrighty then... she's hittin' the dyno again tomorrow with 10psi
Anyone care to guess at the result? |
BOOOOOOOOOMMMM!!!!! 
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TJ
Silver '82 924 NA 5-Speed Manual |
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Khal
Joined: 26 Sep 2003
Posts: 4872
Location: Sunny and lovely interior BC, Canada
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| Posted: Fri May 12, 2006 7:04 pm Post subject: |
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| tj924 wrote: | | Khal wrote: | Alrighty then... she's hittin' the dyno again tomorrow with 10psi
Anyone care to guess at the result? |
BOOOOOOOOOMMMM!!!!! |
*slow clap* Ha ha ha.
I was waiting for that one.
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tj924
Joined: 15 Jul 2004
Posts: 957
Location: Toowoomba, Queensland, Australia
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| Posted: Sat May 13, 2006 9:33 am Post subject: |
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| Khal wrote: | | I was waiting for that one. |
Your welcome!
BTW, did you go with a new wastegate spring or did McGyver install the Boost Controller for you?
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TJ
Silver '82 924 NA 5-Speed Manual |
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Khal
Joined: 26 Sep 2003
Posts: 4872
Location: Sunny and lovely interior BC, Canada
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| Posted: Sat May 13, 2006 1:15 pm Post subject: |
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OK, so that didn't go as planned...
Nothing bad (car and engine-wise), just the boost controller didn't appear to be functioning correctly 
She'd boost to 12psi -on my boost gauge, which is working properly, before anyone asks -then the overboost switch would cut in (and throw us through the windscreen  ). We did a couple of runs down the street at various settings but no joy, same thing over and over, it just didn't want to play ball.
crunchie 57 suspects that a little rubber o-ring on the needle screw is buggered. He's gonna check it out later. But for now, no boost controller and the dyno session was cancelled 
Oh well, on the plus side, it felt pretty good for that millisecond that it hit 12psi
Strange thing is that the overboost switch isn't supposed to cut in 'til 21psi, according to the manual (not that I was complaining, I don't think 21psi would've been too healthy for the engine!).
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Lizard
Joined: 03 Nov 2002
Posts: 9364
Location: Abbotsford BC. Canada
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| Posted: Sat May 13, 2006 1:50 pm Post subject: |
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did you try it at max both ways? as sometimes they can be backwards.
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Paul
Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin
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| Posted: Sat May 13, 2006 2:11 pm Post subject: |
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The boost switch is more sensitive to quick changes in boost than your gauge witch is on the end of 2 or 3 foot hose.
It easy enough to check your switch's trip point by using your boost gauge, an ohm meter and a compressed air source.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
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Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy. |
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flosho
Joined: 01 Jul 2004
Posts: 3160
Location: Eau Claire, Wisconsin
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| Posted: Sat May 13, 2006 2:41 pm Post subject: |
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| Khal wrote: | OK, so that didn't go as planned...
Nothing bad (car and engine-wise), just the boost controller didn't appear to be functioning correctly
She'd boost to 12psi -on my boost gauge, which is working properly, before anyone asks -then the overboost switch would cut in (and throw us through the windscreen ). We did a couple of runs down the street at various settings but no joy, same thing over and over, it just didn't want to play ball.
crunchie 57 suspects that a little rubber o-ring on the needle screw is buggered. He's gonna check it out later. But for now, no boost controller and the dyno session was cancelled
Oh well, on the plus side, it felt pretty good for that millisecond that it hit 12psi
Strange thing is that the overboost switch isn't supposed to cut in 'til 21psi, according to the manual (not that I was complaining, I don't think 21psi would've been too healthy for the engine!). |
I had a similar run in last week at the track.
I had installed a compressor pressure switch, and tried using that as a boost controller, but it was very finicky. I could crank on it, and it wouldn't change the boost, it would stay at 7 psi.. then all of a sudden if you turn it a bit more, it would boost 20 PSI. It was basically all or nothing.
I have now installed a plain "Manual boost controller"(search on ebay, very simple 8 dollar valve) and it was much easier to set the PSI, I took it out this morning at hit 12 psi and stayed steady... Pulls real nicely!
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Khal
Joined: 26 Sep 2003
Posts: 4872
Location: Sunny and lovely interior BC, Canada
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| Posted: Sat May 13, 2006 3:31 pm Post subject: |
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| Lizard wrote: | | did you try it at max both ways? as sometimes they can be backwards. |
Actually, no. But I'm pretty sure it'd be right. crunchie 57 was using it for months before his engine popped. I'm guessing he had it the right way around. Still, maybe this'll be one of those "d'oh!" moments... I'll give a call and check.
| Paul wrote: | | The boost switch is more sensitive to quick changes in boost than your gauge witch is on the end of 2 or 3 foot hose. |
Yeah, I suggested exactly that to crunchie 57. I figured it might be building boost quicker than the gauge could register it. He agreed it could be the case.
| flosho wrote: | | I have now installed a plain "Manual boost controller"(search on ebay, very simple 8 dollar valve) and it was much easier to set the PSI... |
Yep, that's exactly the sort we were using. I'm sure they work a treat... when they work.
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bass gt
Joined: 02 Dec 2004
Posts: 971
Location: Johannesburg for now!!
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| Posted: Sat May 13, 2006 3:46 pm Post subject: |
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Khal,
Very interesting mate. I've just had the exact same thing. She went back to the dyno after some bits and pieces, and suddenley, anything above stock boost was a pain. Spiking and the like. It seemed my valve is acting a bit strange. It's either stock boost or overboost!! So I've removed it now, and she is making a healthy 155 at the hubs at 10 psi, which equates to 175-180 crank.
However, I've just bought an GReddy EBC off EBay of a bargain, so I'm going to give that a try. I think controlling the wastegate from the top has to be better than restricting the actuator line to it.
I'll keep you posted.
Steve |
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Khal
Joined: 26 Sep 2003
Posts: 4872
Location: Sunny and lovely interior BC, Canada
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| Posted: Sat May 13, 2006 4:30 pm Post subject: |
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| bass gt wrote: | | ...and she is making a healthy 155 at the hubs at 10 psi, which equates to 175-180 crank. |
Ah, it's nice to know I'm close to your power with only 7.5psi... 
| bass gt wrote: | However, I've just bought an GReddy EBC off EBay of a bargain, so I'm going to give that a try. I think controlling the wastegate from the top has to be better than restricting the actuator line to it.
I'll keep you posted. |
Cheers. Yeah, let us know what happens.
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WEASEL149
Joined: 19 Aug 2005
Posts: 595
Location: UK, Sheffield
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| Posted: Tue May 16, 2006 7:11 am Post subject: |
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| bass gt wrote: | Khal,
However, I've just bought an GReddy EBC off EBay of a bargain, so I'm going to give that a try. I think controlling the wastegate from the top has to be better than restricting the actuator line to it.
I'll keep you posted.
Steve |
I've tried both ways and found that controlling the wastegate from the top is much better (and safer).
Restricting the actuator line can give you boost spikes. I had problems doing it that way.
I took a solid pipe from a union screwed into the top of the wastegate, up around the back of the engine and then ran a silicone hose from that to the valve controller.
I think the Greddy will have to be plumbed into the top of the wastegate anyway if it's anything like my Blitz Boost controller. Look out for a switch on the Greddy to set it for external wastegate operation - I think it has one like mine.
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sequential
Joined: 18 Nov 2005
Posts: 500
Location: BANNED
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| Posted: Tue May 16, 2006 4:36 pm Post subject: |
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The turbo smart manual valve is the only one i have seen work correctly when connected in line with the wastegate. it is designed for such unlike standard valves which do not allow the pressure to bleed of in the control line creating an over pressure situation after a couple of seconds.
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112 whp with new 4 valve head and MIS 2 |
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Kenodog
Joined: 25 Jun 2003
Posts: 2669
Location: Vancouver,B.C.
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| Posted: Wed May 17, 2006 4:24 am Post subject: |
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Yep.I've got the TurboSmart two stage controller and it holds steady at any setting I choose.Never fails and it's nice to be able to tool around town at 9 psi then instanly switch to 13 psi to wipe the smiles off many a ricer's face. (Raced a 1990 Skyline the other day.I couldn't pass him but he sure was shocked to see my mug in the rearview no matter what he did.)
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1979 Euro 931, Olive
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1991 Ford Ranger XLT 4x4, Ricky
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